WOODSTOCK TWP. — An investigation continued Friday into a fire that consumed two cottages and damaged two other structures Thursday night at Devils Lake.

Addison Fire Chief Tim Shaw said two state fire marshals were at the scene Friday, one from Jackson and another from Lansing, to help determine the cause of the blaze that destroyed a house at 5004 Clearwater Beach and gutted a home and burned a garage at 5010 Clearwater Beach. The siding of a house at 4990 Glenwood Court was damaged. As of Friday evening, the source of the fire remains undetermined, though gasoline has been ruled out, Shaw said.

Witnesses reported hearing three small explosions as the fire progressed, before a larger explosion rocked the neighborhood and surrounding area. Shaw said a propane tank blew up after the fire began and threw debris that landed about 200 feet away.

“It was probably a 20- or 25-pound piece of metal flying through the air,” Shaw said.

A statement issued Friday by Consumers Energy spokesman Dan Bishop said an investigation by the utility found natural gas was not the cause of the fire.